Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Superconductivity: Properties and Electronic Structure
TT 17.4: Vortrag
Montag, 16. März 2015, 15:45–16:00, H 2053
Suppression of superconductivity in a single Pb layer on Ag/Si(111) — •Augusto Leon-Vanegas1,2, Michael Caminale1, Agnieszka Stepniak1, Hirofumi Oka1, Antonio Sanna1, Andreas Linscheid1, Dirk Sander1, and Jürgen Kirschner1,2 — 1Max Plank Institüt für Mikrostukturphysik — 2Martin Luther Univeristät, Halle-Wittenberg
Recently, superconductivity was reported in a single layer of Pb on Si(111) with a critical temperature of 1.83 K [1]. It has been proposed that the interaction of Pb with the Si substrate provides the electron phonon coupling to support superconductivity in this system [2]. We have used a 3He-cooled STM with a vector magnetic field to study the effect of insertion of a Ag interlayer on the superconducting properties of a single Pb layer on Si(111). In contrast to the experiments on Pb/Si(111), the differential conductance of Pb/Ag/Si(111) does not show a gap indicative of superconductivity even at the lowest experimental temperature of 0.38 K. We ascribe this to the suppression of superconductivity [3]. This result is explained by means of ab-initio calculations, showing that the effect of a chemical hybridization between Pb and Ag/Si occurring at the Fermi level dramatically reduces the strength of the electron phonon coupling. This contrasts with the case of Pb/Si(111), where no overlap between Pb and Si electronic states at the Fermi level is found in the calculations.
[1] Zhang et al., Nat. Phys. 6, 104 (2010)
[2] Noffsinger and Cohen, Sol. State Comm. 151, 421 (2011)
[3] Stepniak, et al., J. Surface and Interface Analysis(2014)